The thing with Action Dan and Science Brian, is that they don’t half go on. And on. But the thing with sound effects is that they don’t necessarily go on long enough to cope with ol’ Blather and Blarney over there. So when a sound effect falls short or runs out midway through a scene, it needs to be strung out somehow. And this is where looping comes in.
Sometimes, looping is simple. You simply copy the sound effect and glue it to the end of itself, instantly doubling its length. Then just repeat as necessary. This most often works with vague or indistinct background noises, such as my old friend, “small quiet room”. And some wonderful souls over at Freesound create sound effects specifically designed to be looped in this way.
But sometimes it’s not that simple. Sometimes when you glue a sound effect to the end of itself, it just doesn’t sound right. This may be because the sound changes considerably over its duration, in which case the jump is particularly noticeable, like a record skipping (for those old enough to remember records…). Even if a sound is fairly consistent throughout, though, you may still get an audible glitch where the two sounds meet. So far I’ve found two ways of dealing with this problem.
The time consuming but generally preferable way
In this method, you have to go digging into the waveform and slowly trim away fractions of the sound, trying to match the levels.
Many a happy hour I’ve spent shaving microseconds off the beginnings and ends of sounds. Well, many an hour.
The simpler but less satisfactory way
I stumbled on this method while wrestling with the unusually large number of effects that needed looping during Episode 19 (winches, waves, seagulls, submarine interior, submarine engine, and so forth). If you cross-fade between the end of one copy of the sound effect and the beginning of another copy, then providing you match the fades precisely, it smoothes out the transition.
Of course, the key word here is ‘precisely’… If you listen closely to the episode, you can occasionally hear where I didn’t get them lined up quite precisely enough. Such shoddy workmanship. If I were Action Dan and Science Brian I’d have me fired. Please..?